The present invention relates generally to apparatus for interchangeably mounting articles. More particularly, the present invention relates to a device which can center and hold circular articles of varying diameter.
Apparatus for interchangeably mounting articles are available in almost infinite variety. Of particular interest to the present invention are apparatus for interchangeably mounting articles having circular peripheries, where the diameter of the individual articles may vary over a fairly large ratio. Exemplary mounting apparatus of this type include optical component holders for mounting lenses, mirrors, beam splitters, gratings, and the like.
Optical component holders themselves may take a variety of forms. One common form comprises a pair of opposed jaws which are spring-mounted on a frame or post. Each jaw is V-shaped and is grooved along its inner surface so that the optical component can be mounted by spreading the jaws apart, placing the article between the jaws, and allowing the jaws to close under the spring tension to hold the component in place. One such optical component holder is commercially available as Catalogue Number 22--8155 (Spring Grip Lens Holder) in Ealing Catalogue Number E100K/190, pages C24 and C25.
While such opposed arm optical element holders are functional, they suffer from being able to accommodate only a relatively limited range of diameters, typically within a ratio of only about 1:2. Moreover, the center point of a circular optical component held in such a device will move relative to a fixed portion of the holder depending on the diameter of the particular component which is being held. Such a characteristic is undesirable when optical components of different diameters are interchanged and it is desirable to maintain centering of the component relative to an externally originating light beam.
A second type of optical component mount which provides for such centering is referred to generally as an "iris" mount. Such iris mounts include three or more pivotably attached arms which are located around the periphery of a circular frame. By adjusting the inward travel of each of the arms equally, the device can hold components of varying diameter so that they are centered concentrically relative to the center of the circular frame. An exemplary iris mounting device is commercially available as "PSC"100 holder with concentric grip" (Cat. No. 178 133), Klinger Catalogue, 1990, page 225.
Although such iris mounts are very useful in theory, it can be difficult to maintain precise alignment of all three arms to assure that the optical component is precisely centered. The design of iris mounts which assure such simultaneous alignment of all three arms can be complicated and the resulting devices are not always sturdy. Additionally, the distance between the center of the object being held and the periphery of the holder is always large, making it difficult to position optical elements to receive closely spaced light beams.
For these reasons, it would be desirable to provide alternative designs for mounting apparatus having the capability of holding and centering circular articles having varying diameters. It would be particularly desirable if the device could hold circular articles having diameters which vary over a range greater than 2:1, preferably greater than 3:1, and more preferably greater than 10:1. Such devices should have a minimum number of working parts and should be of sturdy construction so that it is easy to maintain alignment of the parts. It would be particularly desirable if the device could be adapted to act as a grasping element or a gripping element on a robotic arm or other assembly for capturing circular articles at a first location and moving them to a second location.